Electronic superchargers work great!! If properly installed
(This can also be done with a belt driven GM smog pump)
Start with a Craftsman Riding mower w/12hp Briggs.
Mix up 1 gal of 93octane with 16oz of rubbing alcohol and 1 capful of acetone based fingernail polish remover. (acetone bonds alcohol to gas)
Wire 2 9v batteries together in series to make 18v. This will run the "blower"
Install the "blower" to the 12hp briggs motor with some ingenuity, add your fuel, lean out the mixture on the carb a lil. Done
Other things to make it better.
*Change out the 11" pulley on top of the trans, with a 7" one. With this done you will actually have to use the clutch and shift, It will not start off in high gear this way.
*Make a header. Mount a straight piece of 1" pipe to the exhaust port, draw a line down it with a crayon. Ride your mower around for 5min, cut the pipe where the crayon stopped melting off.
*Shave the head. Glue a piece of sandpaper to a piece of glass. Work the head in a figure-8 pattern on the sandpaper. Use clay to check for valve clearance.
Note, this is not legal in actual lawnmower races. Have fun, I did